Alexander U.S. Pat. No. 4,419,100 discloses a two-piece ostomy appliance in which a faceplate component 12 includes a coupling ring 37 attached by thin annular web 42 to a mounting collar 30a which in turn is joined by heat seals 46 and 47 to microporous patch 30. An annular skin barrier layer 32, commonly formed of a hydrocolloid-containing moisture-absorbing and swellable adhesive material having both dry and wet tack, covers the inner portion of patch 30. To protect the bodyside surface of the skin barrier layer and the adhesive coating of that portion of the microporous patch that extends outwardly beyond the skin barrier layer, release sheets 31 and 33 separately cover each of the adhesive surfaces.
The need for providing two release sheets, one for the barrier layer and the other for the surrounding adhesive surface of the microporous patch, arises partly from cost and production considerations since the surfaces the respective release sheets cover are offset and therefore cannot easily be protected by a single release sheet and certainly not by one that is planar. While a molded release covering of developed shape has been disclosed, for example, in Bryson U.S. Pat. No. 4,710,182, such a molded covering is relatively expensive, especially since it is intended primarily to serve a protective function only until the faceplate is to be used, at which time the covering must be removed and discarded. On the other hand, providing separate protective release sheets increases the manipulative steps required by a user at the time of application and also has the disadvantage of exposing the outer edge of the skin barrier material to possible drying by exposure to air during storage prior to use. Also, if the soft, pliant barrier material has any tendency to cold flow, an arrangement utilizing two separate release sheets may be ineffective in maintaining the pliant barrier in fully covered condition prior to use.
Cartmell, et al U.S. Pat. No. 5,489,262 discloses a wound dressing having a hydrogel patch and a transparent adhesive-coated backing layer that extends outwardly beyond the outer limits of the hydrogel patch. A unitary and generally planar release sheet covers both the opposite surface of the hydrogel patch and the adhesive coating of that portion of the backing layer extending outwardly beyond the patch; however, a tenting effect results in which an annular zone of entrapped air extends about the patch and may result in undesirable drying during storage of either or both the hydrogel and the adhesive coating of the backing layer immediately surrounding the hydrogel patch.
Accordingly, a main aspect of this invention lies in providing an improved faceplate construction and its method of manufacture. A unitary release sheet protects the bodyside (rear) surfaces of a barrier layer and of an adhesive-coating covering layer that covers the opposite (front) surface of the barrier layer and projects outwardly beyond the periphery of that barrier layer. The rear surface of the barrier layer is tapered or beveled, and the contoured release sheet follows the bevel of the barrier layer and contacts the adhesive coating of the covering layer immediately adjacent the feathered outer edge of the barrier layer.
The porous covering layer is ideally formed of a soft thermoplastic fabric so that such layer may be joined by heat-sealing to a coupling ring, or to the flexible web for such a ring, or even directly to the thermoplastic film of a collection pouch. In any event, the heat seal zone extends around the stoma-receiving opening of the faceplate and seals or closes the pores of the covering layer in that zone to prevent the outward migration of fluids through the covering layer when the product is in use.
The method of this invention utilizes the injection and compression molding procedure disclosed in Botten et al U.S. Pat. No. 5,716,475 in which discrete mounds of soft, pliant barrier material are deposited one-by-one on an intermittently-advanced web, covered by a second web, and then compressed into the desired shape. In the present method, the second of such webs is the precursor for the unitary release sheet of the finished product. Following injection/compression molding of discrete mounds of barrier material between the two webs, and the replacement of the first web by a third web which is the precursor for the porous covering layer of the finished product, coupling ring elements are successively attached by heat sealing to the porous web. The final stages of the continuous in-line operation involve cutting a stoma-receiving opening through both webs as well as through the barrier material and the drumhead membrane of the coupling ring, followed by a final cutting step that defines the outer peripheral edge of the final product.
Other features, advantages and objects of the invention will become apparent from the specification and drawings.